把input中搜索到的最后一个search替换成format。
outputiterator replace_nth_copy (outputiterator, input, search, format, n);
sequence replace_nth_copy (input, search, format, n);
void replace_nth (input, search, format, n);
outputiterator ireplace_nth_copy (outputiterator, input, search, format, n, local);
sequence ireplace_nth_copy (input, search, format, n, local);
void ireplace_nth (input, search, format, n, local);